The goal of this project is to assess the value of the calcium channel blocker verapamil in the treatment of patients with hypertrophic cardiomyopathy. The drug has now been administered to over 200 patients with this disease and has improved the symptomatology in the majority of these patients for as long as four and one-half years. One must watch closely, however, for adverse effects from verapamil administration. We are presently examining the mechanism of the beneficial effect of this drug, comparing it with other agents in terms of efficacy, and testing beneficial and adverse effects of its co-administration with other agents.